Reticulocytes are immature red blood cells that form an intermediate stage in the development of fully mature red blood cells. During their maturation process, they lose their cell nucleus, which is an important part of their specialization to transport oxygen in the blood. Although the reticulocytes already lack a cell nucleus, they still contain some remnants of organelles, such as ribosomal RNA (rRNA), which is used to complete the synthesis of hemoglobin – the oxygen-carrying protein. When the reticulocytes fully mature and become mature red blood cells, these remnants of organelles and RNA also disappear. Mature red blood cells thus lack both cell nuclei and organelles, which optimizes their shape, flexibility and capacity to transport oxygen.
What Can Abnormal Levels Indicate?
Elevated or low levels of reticulocytes can be indicative of several different medical conditions.
Reticulocytosis: Elevated levels may indicate a response to blood loss, hemolysis, or other blood disorders.
Reticulocytopenia: Low levels may suggest nutritional deficiencies, bone marrow disorders, or chronic illnesses. Mildly low values can be identified in anemia or erythropoiesis, such as in cases of iron deficiency, vitamin B12 deficiency, and folate deficiency.